US4509980A - Electrical contact material comprising silver, cadmium oxide and cupric salt - Google Patents
Electrical contact material comprising silver, cadmium oxide and cupric salt Download PDFInfo
- Publication number
- US4509980A US4509980A US06/496,236 US49623683A US4509980A US 4509980 A US4509980 A US 4509980A US 49623683 A US49623683 A US 49623683A US 4509980 A US4509980 A US 4509980A
- Authority
- US
- United States
- Prior art keywords
- silver
- powder
- electrical contact
- cadmium oxide
- compact
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H1/00—Contacts
- H01H1/02—Contacts characterised by the material thereof
- H01H1/021—Composite material
- H01H1/023—Composite material having a noble metal as the basic material
- H01H1/0237—Composite material having a noble metal as the basic material and containing oxides
- H01H1/02372—Composite material having a noble metal as the basic material and containing oxides containing as major components one or more oxides of the following elements only: Cd, Sn, Zn, In, Bi, Sb or Te
- H01H1/02374—Composite material having a noble metal as the basic material and containing oxides containing as major components one or more oxides of the following elements only: Cd, Sn, Zn, In, Bi, Sb or Te containing as major component CdO
Definitions
- This invention relates to silver and cadmium oxide powder compacts for use in making electrical contacts and to sintered contacts made therefrom and pertains more specifically to the inclusion of a water soluble cupric salt and, optionally, silver oxide, or silver oxide and barium hydroxide, in such compacts to provide sintered contacts having high density and improved resistance to erosion in use.
- the initial density of the sintered powder compact and its resistance to erosion during use can be increased by including in the powder compact copper nitrate in an amount equivalent to 100 to 500 parts per million of copper metal based on the total weight of silver and cadmium oxide; in a preferred embodiment there is also included from 0.1 to 1.5% by weight of silver oxide and 30 to 100 ppm of barium in the form of barium hydroxide based on the total silver and cadmium oxide.
- the powder compact of the present invention comprises a mixture of silver powder and cadmium oxide powder in which the silver amounts to 70 to 95% by weight of the total, preferably 85 to 90%, and the mixture contains from 100 to 500 ppm of copper in the form of a water soluble cupric salt such as the nitrate, sulfate, acetate, or the like, based on the total weight of silver and cadmium oxide.
- the powder compact also includes 0.1 to 1.5% silver oxide by weight and 30 to 100 ppm of barium in the form of barium hydroxide, based on the total silver and cadmium oxide.
- the presence of alkali or alkaline earth metal salts in the compact has no deleterious effect upon the sintered product and may be desirable in small amounts (up to about 0.5% by weight) in providing a still further increase in initial density.
- the increased erosion resistance of the contacts of the present invention results from a decrease in the amount of nitrogen gas entrapped within the sintered contact material.
- the addition of silver oxide which decomposes at low temperature into silver and oxygen helps to displace the entrapped nitrogen.
- Such entrapped nitrogen originating in the atmosphere, is insoluble in the mixture of silver and cadmium oxide and remains within pores of the contact material in compressed form after coining or rolling. As the contact material erodes during the electrical switching and arcing, these compressed nitrogen gas pockets erupt and contribute to excessive spitting type erosion.
- the particle size of the powder components of the compact is not critical and powders of conventional particle size can be used, e.g. silver particles from 1 to 3 micrometers in diameter and cadmium oxide particles from 0.5 to 1.5 micrometers in diameter.
- the cupric salt can itself be mixed with the powder ingredients in the form of a solid powder of approximately the same particle size, i.e. 0.5-3 micrometers, or it can be used in the form of an aqueous solution or a solution in methyl alcohol of any desired concentration which is stirred into the powder mixture.
- cupric salt as used herein includes both the anhydrous salt and the hydrates thereof, e.g. the hexahydrate.
- the silver oxide when employed can also be in the form of a solid powder of approximately the same particle size as the other powder components.
- the powder After mixing in the usual manner, the powder is subjected at room temperature to pressure from 4,000 to 20,000 psi to form a powder compact which can then be sintered in the conventional manner by heating at 850° to 920° C. to form a sintered contact material having a density upwards of 92% of the theoretical and displaying increased erosion resistance during use as compared with similar contacts from which the copper has been omitted.
- the sintered contact materials thus prepared were rolled to a thickness of 0.2 centimeter, then fabricated into contacts one centimeter square and bonded to a copper conductor under identical conditions.
- the contacts were then tested under identical conditions by switching a current of 750 amps at a potential of 575 volts with a power factor of 35%, and breaking a current of 125 amps at 95 volts with a power factor of 35%.
- the contacts of the present invention were found to have lost 0.05 cubic centimeter of their original volume, while the contacts from which the copper sulfate and silver oxide had been omitted lost twice as much, approximately 0.1 cubic centimeters.
Abstract
Description
Claims (9)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/496,236 US4509980A (en) | 1983-05-19 | 1983-05-19 | Electrical contact material comprising silver, cadmium oxide and cupric salt |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/496,236 US4509980A (en) | 1983-05-19 | 1983-05-19 | Electrical contact material comprising silver, cadmium oxide and cupric salt |
Publications (1)
Publication Number | Publication Date |
---|---|
US4509980A true US4509980A (en) | 1985-04-09 |
Family
ID=23971809
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US06/496,236 Expired - Lifetime US4509980A (en) | 1983-05-19 | 1983-05-19 | Electrical contact material comprising silver, cadmium oxide and cupric salt |
Country Status (1)
Country | Link |
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US (1) | US4509980A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030112117A1 (en) * | 2001-07-18 | 2003-06-19 | Ikuhiro Miyashita | Thermal fuse |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB588652A (en) * | 1944-03-08 | 1947-05-29 | Igranic Electric Co Ltd | Electrical contact materials and contacts and methods of making the same |
US3893820A (en) * | 1971-10-27 | 1975-07-08 | Square D Co | Cu-{8 Ag{9 -CdO electric contact materials |
US3969112A (en) * | 1974-11-11 | 1976-07-13 | Gte Laboratories Incorporated | Process for preparing silver-cadmium oxide alloys |
-
1983
- 1983-05-19 US US06/496,236 patent/US4509980A/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB588652A (en) * | 1944-03-08 | 1947-05-29 | Igranic Electric Co Ltd | Electrical contact materials and contacts and methods of making the same |
US3893820A (en) * | 1971-10-27 | 1975-07-08 | Square D Co | Cu-{8 Ag{9 -CdO electric contact materials |
US3969112A (en) * | 1974-11-11 | 1976-07-13 | Gte Laboratories Incorporated | Process for preparing silver-cadmium oxide alloys |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030112117A1 (en) * | 2001-07-18 | 2003-06-19 | Ikuhiro Miyashita | Thermal fuse |
US6724292B2 (en) * | 2001-07-18 | 2004-04-20 | Nec Schott Components Corporation | Thermal fuse |
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AS | Assignment |
Owner name: CHEMET CORPORATION ATTLEBORO, MA A CORP. OF MA Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:JOST, ERNEST M.;REEL/FRAME:004132/0463 Effective date: 19830509 Owner name: CHEMET CORPORATION, MASSACHUSETTS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:JOST, ERNEST M.;REEL/FRAME:004132/0463 Effective date: 19830509 |
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